In a few minutes, the President will try and achieve what his critics say is next-to-impossible: Defend his foreign policy.

Remember this is the man who won a Nobel Peace Prize barely before his Presidency began. And yet in the years since then, Barack Obama has been a feeble spectator over the greatest humanitarian crisis of recent times, the catastrophic Syrian civil war.

The Middle East peace process has unravelled to the point that the US has been forced to step aside and admit there is no realistic chance of progress.

Relations with Russia are at a Cold War-level of mistrust. The President's opponents say he has failed to take a strong or principled stand in Ukraine or Egypt.

So when he shortly steps out at West Point to address these critics, he must somehow convince Americans - and the world - that there is a meaningful Obama doctrine.

He will argue America must be engaged, not isolationist. Internationalist but not instinctively interventionist.

The White House projects this as the nuanced, thoughtful middle course.

But it is a tough sell to a world that sees America floundering to respond amid a growing range of international crises.